Evaporator



Jan. 13, 1959 H. c; BECHTLER- 2,868,279

EVAPORATOR Filed March 17, 1951 4 Sheets-Sheet 1 4 /4 ,2, INVENTOR HANSC. BECHTLER ATI'OR Jan. 13, 1959 H. c. BECHTLER EVAPORATOR Filed March17, 1951 4 Sheets-Sheet 4 INVENTOR HANS C. BECHTLER A'ITORNEKS UniteStats atent ice EVAPORATOR Hans C. Bechtler, Zurich, Switzerland,assignor, by mesne assignments, to Rodney Hunt Machine Company, Orange,Mass, a corporation of Massachusetts Application March 17, 1951, SerialNo. 216,217

8 Claims. (Cl. 159-6) The present invention relates to apparatus forevaporating and concentrating liquids and more particularlyevaporator-concentrators of the thin-film type.

U. S. patent application Serial No. 770,709 filed August 26, 1947, nowabandoned, by Hans Karl Muller forApparatus for Evaporating andConcentrating Liquids, shows a thin film evaporator-concentrator of thetype to which the present invention relates.

The apparatus of applicationSerial No. 770,709 is disclosed in somewhatschematic form and had certain deficiencies from the standpoint ofmanufacture and assembly and in'the case with which the parts can besterilized or cleaned. The present invention overcomes thosedeficiencies. The apparatus disclosed in Serial No. 770,709 is claimedin application Serial No. 216,214, new Patent No. 2,596,086, filedconcurrently herewith by Hans Karl Muller and entitled Apparatus forEvaporating and Concentrating Liquids which latter application is acontinuation-in-part of application Serial No. 770,709.

Thin film evaporator-concentrators are used for the evaporation orconcentration of a wide variety of liquids including various chemicals,food products, pharmaceuticals, blood plasma and the like. Inconcentrating or evaporating food products, pharmaceuticals, blood,

plasma and the like, sterile conditions are essential and with manychemicals extreme cleanliness is required to avoid contamination.

Application Serial No. 770,709 shows an evaporatorconcentrator reducedto its simplest form in order to illustrate the principle involved. Thatapparatus will effectively evaporate or concentrate liquids but, as isreadily apparent, the apparatus is not readily disassembled for cleaningand sterilizing, its parts are not readily accessible, the concentrateis not fully protected from overheating, and it lacks various otherfeatures and refinements of the present invention.

The present invention overcomes the deficiencies of the apparatus ofapplication Serial No. 770,709 and one of the principal objects of thepresent invention is to provide an efiicient evaporator-concentratorwhich may be readily cleaned or sterilized.

Another object is to provide a thin film evaporatorconcentrator in whichthe liquid being treated is protected from contamination.

Another object is to provide a thin film evaporatorconcentrator whichmay be readily disassembled and reasserts Patented Jan. 13,

In the drawing:

Figure 1 is a vertical section of the upper part of anevaporator-concentrator embodying the present invention.

Figure 2 is a vertical section of the lower part thereof.

Figure 3 is an enlarged vertical section of the drive connections forthe rotor of my evaporator-concentrator.

Figure 4 is a section taken on line 44 of Figurel.

Figure 5 is a fragmentary vertical section of a modified form of rotorconstruction.

Figure 6 is a section taken on line 6-6 of Figure 5.

Figure 7 is a fragmentary section of the upper end of a modified form ofvane.

Referring particularly to Figures 1 and 2, the apparatus is of elongatedtubular construction and is normally operated in vertical position. Thelower portion, indicated generally at 10, is the evaporator'portion ofthe apparatus and the upper portion, indicated generally at 12, is theseparator portion. The liquid to be concentrated is introduced through apipe or fitting 14 which is generally located between the evaporatorunit 10 and separator unit 12 and flows down through the evaporatorsection 10 by gravity. The concentrated liquid is withdrawn through apipe or fitting 16 at the bottom of the apparatus and vapor isdischarged through a pipe or conduit 18 above the separator 12.

The evaporator portion has a wall 20 which is normally cylindricalthroughout the entire length of the evaporating chamber. This wall 20may be tapered to form a frusto-conical rather than a cylindricalchamber and, while a cylindrical chamber is ordinarily preferred, it isto be understood that the term cylindrical when applied to theevaporator includes also a chamber of tapered or conical form.

The evaporator and separator units 10 and 12 may be made integral but Iprefer to form the two units separately and to secure them togetherimmediately below the inlet 14. For this reason, the upper end of thewall 20 is provided with an outwardly projecting flange 22 and the lowerwall portion 24 of the separating unit 12 is provided with acorresponding flange 26. The two units 10 and 12 are secured together bybolts 28 and a suitable gasket 30 is provided between the flanges 22 and26. The separating chamber proper, indicated generally at 32, may be ofthe same diameter as the evaporating chamber 10 or may be larger orsmaller, but in the preferred form, the separating chamber 32 formed bythe wall 34 is of larger diameter than the evaporating unit formed bythe wall 20 and the walls 24 and 34 of the separating unit 12 areconnected by a conical wall 36.

A flange or ring 38 is secured around the upper end of wall 34, abovethe pipe or conduit 13, and is reinforced by braces 40 secured aroundthe top of wall 34. These braces 40 may be welded to the ring 38 and tothe wall 34.

A cap 44 is removably secured on the top of wall 34 w and flange 38 byswing bolts 46 and a suitable gasket 48 is usually provided to insure apressure-tight seal.

An extension 50 on top of the cap 44 carries a bearing housing 52 at itsupper end for receiving suitable bearings indicated generally at 54 andcomprising a horizontal ball bearing 53 shown in Figure 1 and a verticalball bearing 55 shown in Figure 3. The specific con- A water sealindicated at 66 may be located between the stuffing boxes 62 and 64.Water is supplied to the seal through a pipe 67 and is dischargedthrough a similar pipe 68. A pipe 69 drains off any lubricant or liquidwhich may collect in the space between extensions and 60. p

A conical wall or shield '70 extends between the joint of wall 34 andcap 44 and the lower end of the sleeve to protect the sleeve 60, thepressure seal and the bearing 54 from the hot vapors. By thisconstruction only the shield 70 need be of stainless steel and the cap44 and other parts may be of less expensive material such as cast iron.The shield 70 is secured to the sleeve 60 by a ring 72 and bolts 74which also support the lower stufling box 64. A similar ring 76 bearsagainst the top stufling box and pressure may be applied to the stufiingboxes and seal by one or more bolts '78 which are accessible through theopening 80 in extension 50.

The drive connections for the rotor are shown paricularly in Figures 1and 3. A flanged ring 82 is threaded on the upper end of the hollowshaft 56 and secures the shaft 56 to the bearing 54. A pulley 84 isfastened to the flanged ring 82 by bolts 86 and has teeth or splines 88which mesh with teeth or splines 90 on the top of hollow shaft 56 toconnect shaft 56 to the pulley 84. A shaft 92 is slidable within thehollow shaft 56 and has splines 94 at its upper end which mesh withsplines 96 on the pulley 84 so that the shaft 92 is longitudinallyslidable but rotatively fixed relative to pulley 84.

The upper end of the shaft 92 has a tapped bore 98 in which a projection100 on head 102 is threaded. The head 102 has an operating handle 104 sothat the head can be rotated to disconnect the projection 100 and head102 from the shaft 92.

The head 102 is normally held against rotation relative to the pulley 84by a detent 106 which normally engages in one of a series of notches 108in the upper face of the pulley 84. The detent 106 is carried by ahollow member 109 which is slidable toward and from the pulley 84 in abore 110 in the head 102. A plate 112 extends across the bore 110 and isprovided with a pin 114 which extends into a hole 116 in the head 102. Aretainer 118 fastened to the side of the head 102 by a screw or bolt120, holds the plate 112 in position. A compression spring 122 betweenthe plate 112 and the member 109 urges the detent 106 downward intoengagement with a notch 108 in the pulley 84 to form a drivingconnection between the pulley 84 and the shaft 92.

The member 109 has ears 124 which extend upward above the plate 112 andcarry a pin 126 on which a cam lever 128 is pivotally mounted. When thiscam lever 128 is turned counterclockwise as viewed in Figure 3, the end130 engages the plate 112 and raises the member 109 against the spring122 disengaging the detent 106 from the notch 108 and freeing the head102 for rotation. The outer end of the cam lever 128 is weighted asindicated at 132 so that if the apparatus should be started with the camlever in upright position and the detent 106 disengaged, centrifugalforce will move the cam lever to the horizontal position shown in Figure3 and permit the detent 106 to engage in north 108 and lock the head 102against rotation relative to the pulley 84.

The head 102 has a central bore 134 which extends through the projection100 and a rod 136 is slidable in this bore. The rod 136 has an enlargedhead 138 at its upper end and a transverse pin 140 at its lower end toprevent removal of the pin 136 from the bore 134. A transverse bore 142extends across the head 102 adjacent the top of the rod 136 so that theposition of the enlarged head 138 of the rod 136 may be observed.

A thrust bearing 144 is secured on the lower side of 4 the head 102 by aretainer 146 and this retainer is held in place by pin 148 and a screw150. This thrust bearing 144 reduces friction between the head 102 andpulley 84 when the head is turned relative to the pulley.

The interior of the hollow shaft 56 has one or more spaced constrictions152 and the shaft 92 has one or more matching spaced enlargements 154 sothat the two shafts 56 and 92 are maintained concentric throughout theirlengths.

The lower end of the shaft 92 is enlarged as indicated at 156and theenlargement 156 has a flat top shoulder 158 and a flat bottom face 160.The lower end of the shaft 56 is provided with an annular gasket 162which engages the top shoulder 158 of enlargement 156 to form a tightseal between shafts 56 and 92 when the head and projection 100 arescrewed into tight engagement with shaft 92.

The rotor 164 of the apparatus could be a solid shaft but is preferablyof tubular construction to save weight and cost and a plug 166 isrigidly secured in the upper end of the rotor 164 by a force fit or bywelding or the like. The enlargement 156 on the shaft 92 is detachablysecured to the plug 166 by screws or bolts 168. A cap or cover 170surrounds the enlargement 156 over the screws or bolts 168 and issecured to the enlargement 156 by a force fit, screw threads or the liketo protect the connection between shaft 92 and rotor 164 from thevapors.

The connection between shaft 92 and rotor 164 may be reached through thehandhole 43 which is usually opposite the pipe or conduit 18. Areinforcing ring 172 is secured around the outer end of the handhole 43and a door 174 pivoted at 175 on a bracket 176 is releasably locked by aswing bolt 177 to close the handhole. A gasket 178 may be provided inthe ring 172 to form a pressure seal between the handhole 43 and thedoor 174. A handle 179 may be secured to the door 174 for convenientoperation. The handhole 43 is sufficiently large to permit a workman toreach into the interior of the apparatus to make adjustments or repairs.A

In the preferred form of my apparatus illustrated in the drawing, therotor 164 extends through the entire length of the separating chamber 12and evaporating chamber 10 and has a fitting 180 which is threaded,welded or otherwise rigidly secured in the lower end of the rotor. Astub shaft 181, in axial alinement with the shafts 56 and 92 isthreaded, welded or otherwise firmly secured in the fitting 180 andprojects downwardly therefrom.

An outwardly projecting flange 182 is welded to the bottom of the wall20 and a conical bottom member 184 having a cylindrical upper portion186 of substantially the same diameter as wall 20 is provided with aflange 188 which is secured to the flange 182 by swing bolts 190. Agasket 192 forms a seal between the flanges 182 and 188.

A sleeve 194 is welded in the bottom of the conical bottom member 184and is provided with a mounting flange 196. A second sleeve 198 carryinga bearing 200 for the stub shaft 181 fits within the sleeve 194' and isprovided with a flange 202 which is secured to the mounting flange 196by bolts 204. The lower end of the sleeve 194 is closed by a plate 206having a drain plug 208. The sleeves and flanges of this lower bearingmounting have pressure-tight connections and the stub shaft 181 andbearing 200 are cylindrical or slightly tapered to permit readywithdrawal and reinsertion of the shaft 181 in the bearing 200. Ashoulder 209 on the stub shaft 181 limits the downward movement of theshaft into the bearing 200.

A sleeve 210 encircles the wall 20 and is welded to the flanges 22 and182 in spaced relation to the wall 20, forming a jacket for steam, hotwater or other heating medium for the evaporating chamber portion 10. An

expansion joint 212 may be provided in the sleeve 210 plurality ofperforations 218 to direct the steam downward and against the wall 20 toheat the wall uniformly. An attaching flange 220 is welded to the outerend of the pipe 214 for attachment to a source of steam not shown.

A pipe 222 is secured in an opening in the sleeve 210 at the bottom ofthe steam jacket to permit removal of the cooled or condensed steam andmay be attached to a pump or trap, not shown, by a flange 224. Whensteam is first introduced into the jacket, the jacket is filled with airand a pipe 226 may be provided at the top of the jacket as an air bleed.This pipe 226 has a flange 228 to which a suitable valve, not shown, maybe attached and this valve will ordinarily be closed as soon as all ofthe air in the jacket is replaced by steam. The valve connected to thepipe 226 would normally be kept closed during the operation.

Condensation of steam on the wall 20 tends to insulate the wall andimpede the transfer of heat. For that reason, it is desirable thatcondensation on the wall be kept at a minimum. In order to enhance thetransfer of heat and reducecondensation, a plurality of annular rings230 are welded to the wall 20 at spaced intervals between the flanges 22and 182 which form the upper and lower ends of the steam jacket. In theembodiment shown, the rings 230 are of rectangular cross section andeach has an annular groove 232 in the lower surface near the outer edge.Condensate forming above a ring 230 runs down the wall 20, and over thering 230 and, because of the lip formed at the outer edge by the groove232, this condensate drops downward away from the wall 20. The rings23f) also reinforce the wall 20 and serve as fins to enhance thetransfer of heat from the steam to the wall 29. His desirable from botha strength and a heat transfer standpoint to use a number of rings 230within the steam jacket but the welding of the rings to the wall maydistort the wall and, since even small distortions have an adverseeffect, great care must be taken during the welding and usually only afew, relatively widely spaced rings are used. Various other structuresfor improving the transfer of heat to the wall 20 and minimizing theinsulating effect of condensation are shown in Swiss Patent No. 266,552.

The rotor 164 is imperforate throughout its length and is sealed at bothends. The rotor 164 is smaller than the evaporating chamber 16 formed bythe wall 20 and within the chamber 10, the rotor is provided with aplurality of blades or vanes 234 which extend outward from the rotorinto close proximity with the wall 20. In the embodiment shown inFigures 1, 2 and 4, there are four equally spaced vanes 234 whichproject radially outward toward the wall 20. Ordinarily the vanes 234are fiat strips of metal or the like and are preferably rigidly securedalong one entire edge to the rotor 164 by welding or the like. It is notessential that the vanes 234 be flat radially nor that they extendlongitudinally along the rotor but the flat longitudinal vanes aresimpler to make and attach to the rotor and are also lighter in weight.

The vanes 234 are continuous longitudinally and extend from the rotoroutward into close proximity with the wall 20 so that every part of thespace between the rotor and the wall is acted upon by the vanes when therotor is rotated. Holes, notches or perforations in the vanes 234 willnot prevent satisfactory operation so long as liquid cannot pass fromthe inlet 14 to the outlet 16, and liquid or foam cannot collect orremain in the steam jacketed portion of the evaporator unit 10, withoutbeing acted upon by the vanes.

s asms The clearance between the vanes 234 and the Wall 20 is kept assmall as possible within reasonable mechanical limitations. Any numberof vanes may be used but, because of the small clearances, it isimportant that the rotor 164 be balanced and the vanes are thereforesymmetrically disposed about the rotor. In some instances, twooppositely disposed vanes extend into close proximity to the wall 20while the other vanes are somewhat narrower as shown in Figure 6 andhereinafter described.

As shown in Figure 2, the rotor 164 and vanes 234 extend a substantialdistance below the bottom of the steam jacket. The liquid at the lowerpart of the evaporator 10 is usually quite thick and thickened liquid orfoam is permitted to collect and stand in this lower portion. The vaneportions below the steam jacket keep any such liquid and foam agitatedand, by stopping the steam jacket short of the bottom, the liquid andfoam are protected from excessive heat.

The bearing 200 may be formed of suitable material such as graphite or arubber-graphite composition or white metal, bronze, babbit or the likeand both the hearing and stub shaft 181 of the rotor are exposed to theliquid being concentated so that the liquid serves as a lubricant. Whenthe bearing is to be cleaned, as for example when the apparatus is to beused to concentrate a different liquid, the plug 208 may be removed andthe bearing assembly flushed out with water.

In the embodiment illustrated, the vanes 234 continue along the rotor upinto the separating chamber 12 and a grid consisting of a plurality ofvertical, radially disposed, spaced baflies 236 and spaced horizontal,annular baffles 238, is positioned in the separating chamber 12 oppositethe upper end of the rotor 164 and vanes 234. The top horizontal baffle238 is preferably above the upper ends of the vanes 234 so thatseparated droplets of foam or liquid will not be carried over with thevapor. The lower ends of the baffles 236 are tapered to seat on theconical wall portion 36 and the horizontal and vertical baffies 236 and238 are preferably welded together so that the entire grid may beinserted or removed from the separating chamber as a unit. There ispreferably a clearance between the horizontal baffles 238 and the wall20 so that the liquid can run down the wall 22 without interference butthe top horizontal bafile 238 may have a tight fit with the wall 34 toprevent separated liquid from creeping upward along the wall 34. Thebaflies 236 and 238 extend inward into close proximity to the vanes 234so that the vapor cannot pass through the separating chamber withoutbeing acted upon by the vanes.

As positioned out above, the evaporator is operated in a verticalposition and mounting brackets 246 may be secured to the apparatus forsecuring the apparatus to suitable supports.

The apparatus is usually operated under a vacuum and a condenser andpump, not shown, which may be of any suitable construction, are attachedto the flange 242 on the vapor outlet conduit 18. The condensate isevacuated through the pipe 16 and a suitable vacuum pump or trap, orboth not shown, which maintain the vacuum.

In operation, the pulley 84 is driven by a suitable source of power suchas an electric motor, not shown. The rotor is rotated rapidly but theexact speed of rotation is not critical. Theoperation is satisfactorywhen the rotor 164 carrying the vanes 234 are rotated at a speed suchthat the circumferential speed of the vanes is in the general range often to fifteen meters per second. i

The liquid to be concentrated is introduced through the pipe 14 which isordinarily above the steam jacket to avoid burning of the incomingliquid and I prefer to locate the fitting 14 between the evaporatingunit 10 and separating unit 12 although it may be located in theseparating chamber 12. If desired, a. plurality of inlet pipes 14 may besymmetrically disposed around 20 to equalize the cooling effect of theincoming liquid and prevent distortion of the apparatus. Notches 244 areprovided in the vanes 234 opposite the inlet pipe 14 so that the vaneswill not intefere with the introduction of the liquid to beconcentrated. In my preferred form, the inlet 14 extends a shortdistance through the wall 24 and is provided with a lip 246 to directthe incoming liquid downward toward the evaporating chamber 10.

The wall 20 is heated by introducing steam at the desired temperatureand pressure and the vanes 234 force the liquid out against the heatedwall 20 in a thin film. The liquid flows down the wall 20 by gravity tothe bottom of the evaporator unit where it is withdrawn through the pipe16. Because the vanes 234 are substantially continuous'and extend acrossthe entire space between the rotor 164 and the wall 20, all of theliquid passing through the evaporator is being constantly acted upon thevanes. The centrifugal action of the vanes 234 tends to suppress orprevent the formation of foam and to destroy any foam which may beformed.

As the liquid flows down the wall 20, vapor is driven off and this vaporpasses upward between the rotor 164, wall 20 and the vanes 234. Themoving vanes 234 strike droplets of foam or liquid entrapped in thevapor and drive these droplets outward against the wall 20.

Because the rotor 164 is imperforate andthe vanes 234 are substantiallycontinuous longitudinally and radially, the entire contents of theevaporating chamber is at all times subject to centrifugal forceresulting from rotation of the rotor and vanes. This tends to suppressthe formation of foam and to force any foam which may be formed outwardagainst the heated wall 20. There is no place within the steam jacketedportion of the evaporator unit 10 where liquid or foam can collect freefrom the action of the rotating vanes 234.

All of the vapor from the evaporating chamber 10 passes upward throughthe separating unit 12 which is normally unheated except by the vapor sothat ordinarily the temperature in the separating chamber 12 isinsuflicient to cause substantial further evaporation of the liquid. Thepurpose of this separating chamber is to remove any unevaporated foam orliquid carried by the vapor so that operating losses may be kept as lowas possible. In some instances, it may be necessary or desirable tosupply some outside heat to the wall 34 to prevent condensation in theseparating chamber. This may occur when a very long separating chamberis required to ensure extraction of entrapped liquids which are noteasily separated from their vapor. Such heat should however be kept at aminim-um to avoid burning the separated liquid flowing down the wall 20.

In the preferred form of separator shown, the length and speed ofrotation of the rotor 164 and vanes 234 in the separating zone is suchthat the vanes will move through at least the angular distance betweenadjacent vanes while vapor is moving the length of the vanes in theseparating zone so that every part of the vapor passing through theseparating zone is acted upon by a vane 234 moving through the vapor andany entrapped foam or liquid is driven outward by centrifugal forcetoward the wall 34. The vertical baffies 236 prevent rotation of theseparated foam and liquid within the separating chamber and thehorizontal baffles 238 prevent the separated foam and liquid from beingcarried upward by the vapor. Any foam and liquid in the vapor in theseparating chamber 12 is projected outward against the wall 34 by thevanes 238 and flows down the walls 34, 36, 24 and back into theevaporating chamber.

One of the principal features of my invention is the ease with which itcan be taken apart for cleaning and sterilizing without disturbing themore permanent connections of the vapor outlet, concentrate outlet andsteam jacket.

For ordinary cleaning, it is usually sufircient to operate the apparatuswith clean flushing water or with a detergent and then with flushingwater. For a more thorough cleaning, the cam lever 128 is lifted and thehead 102 unscrewed from the shaft 92. As the head 102 is unscrewed, theshaft 92 carrying the rotor 164 is first lowered until the collar 209rests on .the bearing 200 and sleeve 198. With further turning the head102 is completely unscrewed and may be removed. When the swing bolts 46are released, the cap 44 carrying the pulley 84, hollow shaft 56,bearings 54 and seal may be removed as a unit. The interior of theapparatus is then accessible through the open top and the rotor. vanesand walls may be scrubbed with a brush.

After cleaning, the cap 44 and its associated parts are replaced and thehead 102 is again threaded into the shaft 92. The final result of thescrewing action of the head 102 is to raise the rotor to its properposition and the thrust bearing 144 reduces friction during the raisingof the rotor. When the rotor is in its proper operating position, thebottom of the threaded bore 98 in the shaft 92 engages the bottom of pin136 and raises pin or indicating means 136 until the top 138 is visiblein bore 142.

When more complete cleaning or sterilizing is required, the head 102 isleft in place. The head 102, shaft 92 and rotor are then removed as aunit with the cap 44 and may be cleaned and sterilized outside theapparatus. The separator grid may be removed with or without removal ofthe rotor and the entire interior of the apparatus is accessible forcleaning and sterilizing.

The lower cone 184 carrying the lower bearing assembly may be removed asa unit for repair, replacement, cleaning or sterilizing by releasing theswing bolts 190. Throughout the construction, sharp corners or crevicesare avoided as much as possible in order to facilitate cleaning andsterilizing and to eliminate places where bacteria or contaminants maycollect.

Figures 5 and 6 show a modified form of rotor construction. In thismodification, eight vanes are illustrated as formed of two pieces ofsheet metal 252, each piece being bent to form three vanes 254. Eachfree end 256 of each piece of sheet metal 252 is bent outward from therotor 164 and the free ends 256 of both pieces joined together to formthe seventh and eighth vanes indicated generally at 258. The sheet metalpieces 252 may be welded or otherwise firmly secured to the rotor 164.

It is to be noted that there is a substantial clearance between theouter edges of the vanes 254 and the wall 20 of the evaporator unit 10.One or both of the free ends 256 forming vanes 258 extends outward intoclose proximity with the wall 20 of the evaporator chamber 10. Obviouslyin this construction, all of the vanes could be formed from a singlepiece of sheet metal or could be formed of three or more pieces of sheetmetal. It is important however that the rotor and vane assembly beaccurately. balanced and the illustrated construction is preferredbecause of its structural advantages and the ease with which it can bebalanced.

As pointed out above, liquid or foam in the lower part of the evaporator10 may be quite thick, sluggish and susceptible to burning, especiallyif the liquid or foam is permitted to collect and stand in this lowerportion. The vanes 254 and 258 extend below the stream jacket and keepthis thick liquid or foam agitated so that the liquid or foam isprotected from excessive heat.

The construction shown in Figures 5 and 6 further protects theconcentrate from over-heating by forcing the concentrate out of theapparatus. This is particularly important when the concentrate isviscous or semi-solid such as catsup.

The outlet opening 260 is enlarged to facilitate discharge of theconcentrate and extensions 262 are secured to the lower ends of two ormore of the vanes. Figures and 6 show two extensions 262 secured to theoppositely disposed vanes 258. The lower ends of the extensions 262 arebent downwardly and rearwardly at 264 and, when the rotor is turned,these bent ends force the concentrate and foam downwardly and outthrough the outlet 260. If desired, this section may be increased bysecuring inclined blades 266 on the fitting 180. Figure 7 shows theupper end of the modified form of vane in which the upper end isinclined rearwardly of the direction of rotation to prevent dropletsfrom creeping upwards along the vane and being carried away in thevapor. This extension may be a separate piece 270 as shown or may be anintegral part of the blade.

It is apparent that my improved construction can be used for a separatoror for an evaporator but by securing the evaporator and separatorsections together and using a single rotor for both, the construction issimplitied and the cost of the unit is reduced. The apparatus may beconstructed of any suitable material but ordinarily, I prefer to usestainless steel for all parts contacting the liquid because of itscorrosion resistance.

From the foregoing, it will be apparent that I am able to attain theobjects of my invention and provide a new and improved apparatus forconcentrating liquids in which operational losses are minimized.Provision may be made for attaching pressure and temperature gages tothe steam jacket as shown in Figure 2 so that the heating may be closelycontrolled. The parts are so made that the apparatus may be readilydisassembled for cleaning and sterilizing.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiments are therefore to be considered in all respects asillustrative and not restrictive, the scope of the invention beingindicated by the appended claims rather than by the foregoingdescription, and all changes which come within the meaning and range ofequivalency of the claims are therefore intended to be'embraced therein.

What is claimed and desired to be secured by United States LettersPatent is:

1. An evaporator comprising a chamber having a substantially verticalcylindrical wall, an impcrforate rotor rotatably mounted in said chambersubstantially coaxial with said wall, a plurality of vanes radiallyspaced around said rotor and extending outward therefrom into closeproximity with said wall, said vanes being substantially continuouslongitudinally and radially, means for rotating said rotor, means at theupper end of said chamber for introducing liquid to be evaporated,heating means on said wall below said inlet, an outlet for unevaporatedconcentrate at the lower end of the chamber spaced from said heatingmeans, means on said rotor for agitating the concentrate in the spacebetween said heating means and said outlet, and mean secured to thelower ends of said vanes and inclined rearwardly of the direction ofrotation of the rotor for urging the concentrate downward to saidoutlet.

2. Apparatus for evaporating and concentrating liquids comprising asubstantially cylindrical evaporating chamber, a substantiallycylindrical separating chamber connected at one end to one end of saidevaporating chamber coaxially therewith, said evaporating chamber havinga concentrate outlet at the end remote from said separating chamber,said separating chamber having a vapor outlet at the end remote fromsaid evaporating chamber, a fluid inlet adjacent the connection betweensaid chambers, means for heating the wall of said evaporating chamber,an imperforate rotor extending through both chambers substantiallycoaxially therewith, means on said rotor within said separating chambercomprising longitudinally and radially continuous vanes extendinglongitudinally of said rotor and projecting outward therefrom fordriving entrapped liquid in the vapor from said evaporating chamberoutward against the wall of said separating chamber, means on said rotorwithin said evaporating chamber comprising longitudinally and I radiallycontinuous vanes extending longitudinally of said shaft and projectingoutward therefrom into close proximity with the heated wall forspreading liquid in said evaporating chamber in a thin film on saidheated wall, a plurality of blades independent of said vanes mounted onsaid rotor adjacent said concentrate outlet for urging said concentrateto and through said concentrate outlet, and means for rotating saidrotor.

Apparatus for separating entrapped liquid particles from a vapor,comprising a housing having a substantially cylindrical wallconstituting a conduit through which the vapor is passed, a vapor inlet:at one end of said housing and a vapor outlet at the other end of saidhousing, an annular cylindrical cage within said housing, said cagecomprising circumferentially spaced longitudinal baffles extendinginward from said wall and axially spaced transverse baflies inward fromsaid wall and spaced therefrom said baflies being secured together andextending inwardly substantially equidistant from said wall, therebyproviding an axial free space through said housing removably supportingsaid cage within said housing, a rotor having an imperforate surfacerotatably mounted Within said housing for rotation on an axissubstantially concentric with the housing wall, said rotor having asubstantially smaller diameter than the free space within said cage, aplurality of vanes circumferen tially spaced about said rotor, each vanebeing secured along one edge to the rotor and extending outwardly fromsaid rotor into close proximity with the baffles of said cage, saidvanes being substantially continuous from said rotor to said bafllesthroughout the length of said longitudinal bafiies, and means forrotating said rotor whereby said vanes will strike liquid entrapped insaid vapor and drive. such liquid outward toward the housing Wallbetween said baffles while permitting the vapor to pass through thehousing.

4. Apparatus for separating entrapped liquid droplets as defined inclaim 3 in which the vanes are provided with extensions adjacent thevapor outlet inclined rearwardly of the direction of rotation of therotor to prevent liquid from flowing along said vanes.

5. In a ,thin film evaporator, a substantially vertical housing having asubstantially cylindrical wall, a liquid inlet and a vapor outlet, acylindrical bearing at the lower end of said housing substantiallycoaxial with said wall, a cover assembly releasably secured to the topof said housing for closing saidhousing, a rotor for agitating saidliquid extending longitudinally through said housing, a shaft on saidrotor rotatably and slidably journalled in said bearing, a second shaft'rotatably mounted in said cover assembly substantially coaxial with saidrotor, manually operable means Within said housing for detachablysecuring said rotor to said second shaft, manually operable adjustingmeans on said cover assembly for moving said second shaft and rotorlongitudinally of the housing, means on said cover for driving saids=econd shaft, latch means for preventing operation of said manuallyoperable adjusting means, and means operable L when said second shaft isrotated for operating said latch means for preventing operation of saidmanually operable adjusting means.

6. In a thin film evaporator as defined in claim 5, means for indicatingwhen said second shaft is secured to said cover assembly.

7. A thin film evaporator comprising a substantially vertical tubularhousing of substantially circular crosssection throughout its length,the interior surface of said housing being smooth and having no portionof less diameter than any lower portion of the housing, a bearing ofsubstantially circular cross-section fixed at the lower end of saidhousing substantially co-axial with said housing, a rotor rotatablymounted within said housing, vanes '11 extending longitudinally of saidrotor and projecting radially outward therefrom, a shaft projectingdownward from the lower end of said rotor rotatably and slidably mountedin said bearing, a cover assembly releasably secured to the top of saidhousing to close said housing, a member rotatably journalled in saidcover assembly substantially coaxial with said rotor, means on saidcover assembly for rotating said member, means for releasably connectingsaid member and said rotor, and means on said cover assembly for raisingsaid member and said rotor away from said bearing.

8. A thin film evaporator comprising a substantially vertical tubularhousing of. substantially circular crosssection throughout its length,the interior surface of said housing being smooth and having no portionof less diameter than any lower portion of the housing, a hearing ofsubstantially circular cross-section fixed at the lower end of saidhousing substantially coaxial with said housing, a rotor rotatablymounted within said housing, vanes extending longitudinally of saidrotor and projecting radially outward therefrom, a shaft projectingdownward from the lower end of said rotor rotatably and slidably mountedin said bearing, a cover assembly releasably secured to the top of saidhousing to close said housing, a member rotatably journalled in saidcover assembly substantially coaxial with said rotor, drive 12 means onsaid cover assembly for rotating said member, means for releasablyconnecting said member and said rotor, and sealing means between saidhousing and said drive means to prevent vapors in said housing fromreaching said drive means.

References Cited in the file of this patent UNITED STATES PATENTS688,505 'Deibler Dec. 10, 1901 1,039,779 Miles Oct. 1, 1912 1,109,143Perkins Sept. 1, 1914 1,356,082 Merrell Oct. 19, 1920 1,403,804 MerrellJan. 17, 1922 1,451,168 Mabee Apr. 10, 1923 1,876,002 Harper Sept. 6,1932 2,102,548 Stratford Dec. 14, 1937 2,414,521 Gunther Jan. 21, 19472,469,557 Ingraham May 10, 1949 2,542,269 Zahm Feb. 20, 1951 2,542,270Zahm Feb. 20, 1951 2,596,086 Muller May 6, 1952 FOREIGN PATENTS 330,805Great Britain June 19, 1930 UNITED STATES PATENT OFFICE CERTIFICATE OFCORRECTION Patent No. 2,868,279 January 13, 1959 Hans C, Bschtler It ishereby certified that error appears in the printed specification of theabove numbered patent requiring correction and that the said LettersPatent should read as corrected below.

Column 3, line 65, for north read M notch column 6, line 43, for "20"read 34 line 44, for "22" read 34 line 51, for "positioned" read apointed line 58, for "condensate" read concentrate column '7, line 5 for"intefere" read an interfere Signed and sealed this 9th day of June1959.

SEAL) Attest:

KARL H. AXLINE ROBERT C. WATSON Attesting Officer Commissioner ofPatents

